Code highlighting

app.py

@@ -72,6 +72,7 @@ from core.shared import noindex
 from core.shared import paginated_query
 from utils.blacklist import is_blacklisted
 from utils.emojis import EMOJIS
+from utils.highlight import HIGHLIGHT_CSS
 from utils.key import get_secret_key
 from utils.template_filters import filters
 
@@ -153,6 +154,7 @@ def inject_config():
         else 0,
         me=ME,
         base_url=config.BASE_URL,
+        highlight_css=HIGHLIGHT_CSS,
     )
 
 

requirements.txt

@@ -24,3 +24,4 @@ pyyaml
 pillow
 emoji-unicode
 html5lib
+Pygments

templates/layout.html

@@ -21,6 +21,7 @@
     width: 25px;
     height: 25px;
 }
+{{ highlight_css }}
 </style>
 {% block headers %}{% endblock %}
 </head>

templates/utils.html

@@ -77,7 +77,7 @@
     {% if obj | has_type(['Article', 'Page']) %}
         {{ obj.name }} <a href="{{ obj | url_or_id | get_url }}">{{ obj | url_or_id | get_url }}</a>
     {% elif obj | has_type('Question') %}
-        {{ obj.content | clean | replace_custom_emojis(obj) | safe }}
+        {{ obj.content | clean | replace_custom_emojis(obj) | code_highlight | safe }}
 
         
         <ul style="list-style:none;padding:0;">
@@ -146,7 +146,7 @@
 
 
     {% else %}
-	{{ obj.content | clean | replace_custom_emojis(obj) | safe }}
+	{{ obj.content | clean | replace_custom_emojis(obj) | code_highlight | safe }}
     {% endif %}
 	</div>
 

utils/highlight.py

@@ -0,0 +1,30 @@
+from functools import lru_cache
+
+from bs4 import BeautifulSoup
+from pygments import highlight as phighlight
+from pygments.formatters import HtmlFormatter
+from pygments.lexers import guess_lexer
+
+from config import THEME_STYLE
+from config import ThemeStyle
+
+_FORMATTER = HtmlFormatter(
+    style="default" if THEME_STYLE == ThemeStyle.LIGHT else "vim"
+)
+
+HIGHLIGHT_CSS = _FORMATTER.get_style_defs()
+
+
+@lru_cache(512)
+def highlight(html: str) -> str:
+    soup = BeautifulSoup(html, "html5lib")
+    for code in soup.find_all("code"):
+        if not code.parent.name == "pre":
+            continue
+        lexer = guess_lexer(code.text)
+        tag = BeautifulSoup(phighlight(code.text, lexer, _FORMATTER)).body.next
+        pre = code.parent
+        pre.replaceWith(tag)
+    out = soup.body
+    out.name = "div"
+    return str(out)

utils/template_filters.py

@@ -21,6 +21,7 @@ from config import ID
 from config import MEDIA_CACHE
 from core.activitypub import _answer_key
 from utils import parse_datetime
+from utils.highlight import highlight
 from utils.media import Kind
 from utils.media import _is_img
 
@@ -47,6 +48,11 @@ def visibility_is_public(v: str) -> bool:
     return v in [ap.Visibility.PUBLIC.name, ap.Visibility.UNLISTED.name]
 
 
+@filters.app_template_filter()
+def code_highlight(content):
+    return highlight(content)
+
+
 @filters.app_template_filter()
 def emojify(text):
     return emoji_unicode.replace(